Means for insuring complete combustion of coal in heating boilers



Apr. 3, 1923, 1,450,201 R. W. BURCKHARDT MEANS FOR INSURING COMPLETECOMBUSTION OF COAL IN HEATING BOILERS.

Filed Aug. 10, 1920 I Invehtan Patented Apr. 3, 1923.

urr sraas RODOLPHE WILLIAM BURCKHARDT, OF MULHOUSE, FRANCE.

MEANS FOR INSURING COMPLETE COMBUSTION OF COAL IN HEATING BOILERS.

Application filed August 10, 1920. Serial No. 402,731.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 8, 1921, 41 STAT. L,1313.)

T all whom it may concern:

Be it known that I, Ronorrnn IVILLIAM BURGKHARDT, citizen of theRepublic of Switzerland, residing at Mulhouse, Department of theHaut-Rhin, in France, and hav ing I. 0. address Rue Saint-Jean, in thesaid city, have invented certain new and useful Improvements in Meansfor Insuring Complete Combustion of Coal in Heating 10 Boilers (forwhich I have filed application in France, Aug. 1, 1919, and whicheventuated in Patent No. 510,460, dated Aug. 1,

1919, and delivered Sept. 6, 1920; said invention has also been patentedin Belgium, July 24;, 1920, No. 289,599; Great Britain,

July 30, 1920, N0. 149,67 7 Luxemburg, July 30, 1920, No. 11,894; andItaly, July 31,1920,

No. 534/97); and I do hereby declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same.

This invention has reference to means for ensuring complete combustionof the coal used for heating steam boilers and it consists in acombination of devices whereby the different gaseous strata rising fromthe grate of a boiler furnace are intimately mixed, the quantity of coalfed to the furnace and the 0 column of air forced in being regulated inapproximately the theoretic proportions, and the heat abstracted fromthe combustion gases in two stages, the mixing being effected betweenthe said stages, substantially 5 as hereinafter described.

The invention is illustrated in the accompanying drawings, in which:

Fig. 1 is a diagrammatic vertical section of a device embodying theinvention in its preferred form.

Fig. 2 is an enlarged detailed view of a portion of Fig. 1 relating tothe device for mixing, initially, the air and gases.

Fig. 3 is a view similar to Fig. 1,showing the device slightly modifiedin certain details.

Figure 1 illustrates an application of the invention to a boilercomprising two cylindrical boiler drums 1- and 2 connected by means of acluster of tubes 8. The grate t is of the endless platform type fed withcoal from a hopper 5 and with air by means of a blower 6. A horizontalgas-tight partition ed to mix the gaseous strata, which device ispreferably constructed as illustrated in Figure 2, but is not per secomprised in the present invention as it forms the subject matter of a.separate concurrent application for patent filed August 10, 1920, Serial,No. 402.732. 13 indicates a stirring device by means of which thedesired thorough mixing is accomplished.

To enable the steps in the progress of the phenomenon of combustion tobe readily understood, the gases issuing from the furnace may be dividedtheoretically into three strata, indicated by the arrows 9, 10, 11, thestratum 9 with an excess of air, the stratum 10 with a mixture of airand combustible in approximately the theoretic proportions, and thestratum 11 with a great excess of. combustible.

The combustible is fed in by means of the hopper 5 and the theoreticvolume of air is supplied by the blower 6; and the three gaseous stratatraverse the passage across which the lower part of the cluster of tubesextends. In this passage the said gaseous strata become cooled to anextent which depends, it will be understood, upon the dimensions of thisportion of the boiler, and these dimensions should be such that thegases are cooled to a temperature which does not bring them below a dullred colour, so that they can readily burst into flame again. Inpractice, this will correspond to a lowering of temperature of about600.

These gases are not always mixed and they remain separated into threelayers or strata, but they have lost so much of their heat that.intimately mixed and being consumed completely, their temperature willnot exceed that which is dangerous for masonry. It is at this momentthat the gases are mixed by means of suitable devices as illustrateddiagrammatically in the drawing.

The mixing device referred to above which consists of transverse'tubescauses the fractionated strata to pass from one wall to the other ispreferably employed. Mechanical devices made of suitable refractorymaterial and cooled artificially, such as the rotary arms indicated bythe reference numeral 13, may likewise be employed.

The gases, completely mixed and consequently completely consumed, passup into the fine in which the upper part of the cluster of tubes islocated and impart their heat to the said tubes.

hen the boiler is of large dimensions, the passages or flues becomeproportionately large, and the mixing problem increases in difficultybecause the extreme strata are further separated from each other. Inthat case it is advantageous to sandwich, so to speak, a cross currentof air between the various combustible strata, and this is effected byintroducing secondary air through an opening 12, Fig. 1, which airfollows the course indicated by the arrows 12. It will be realized thatthe mixing will thus be more easily eflected. This secondary air is ofcourse not in addition tothe theoretic quantity of air forced in by theblower but is reckoned as part of the total theoretic quantity requiredfor combustion.

Figure 3 shows another way of applying the invention to a boiler of thesame type provided with a Riley grate. The mixing chamber inthis case isarranged at the front of the boiler, and a primary mixing device, suchas described above, consisting of tubes 81 arranged crosswise, isarranged within ,the cluster oftubes above a baffle plate 71, as

indicated in the lower portion 14 of the flue. Complete combustion andthe final transfer of heat tothe tubes take place in the upper portion15 of the flue. In this figure, 13 represents a modified arrangementcomprising a series of obstructions or baflies to further mix or cause acommingling of the gases, corresponding in effect to the rotary stirrers13 shown in Figure 1.

Claims 1. In a furnace, the combination with means for regulating thequantity of coal fed thereto and the volume of air blown in, of a firstboiler element which abstracts a portion of the heat from the combustiongases, cans for thereafter effecting a preliminary mixing of said gases,an obstructed passageway for subsequently causing a more thorough mixingof the gases thus cooled, and a second boiler element around which thecomplete combustion of the mixed gases and the final transfer of theheat to the boiler takes place.

2. In a furnace, thecombination wit-h means for regulating the quantityof coal fed thereto and the volume of air blown in, of a first boilerelement which abstracts a portion of the heat from the combustion gases.astationary honeycomb structure for clfecting the preliminary mixing ofthe gases thus cooled, a rotary mixing device for Subsequently causing athorough stirring of the gases and a second boiler element around whichthe complete combustion of the mixed gases and the final transfer ofheat to the boiler takes place.

In testimony whereof I aflix my signature, in presence of two witnesses.

ROD. WILLIAM BURGKHARDT. \Vitnesses:

VILLIAM E. HOLLAND, FRIDEN LALADIN.

